Polyethylene terephthalate stabilized with a condensation product of a phenol with an unsaturated aldehyde



. each mole of the aldehyde.

United States Patent 3,186,962 POLYETHYLENE TEREPHTHALATE STAEKHZED WHTH A CGNDENSATTGN PRQDUCT 0B A PHENOL WITH AN UNSATURATED ALDEHYDE Derek Ranson, Norton-on-Tees, England, assignor to linperial Chemical Industries Limited, London, England, a corporation or Great Britain No Drawing. Griginal application July 22, 1%0, Ser. No. 44,547. Divided and this application duly 12, 1961, Ser. No. 130,212 Claims priority, application Great Britain, Apr. 14, 1960, 13,444/60 5 Claims. (Cl. 260-4535) This invention relates to tris(hydroxyaryl) compounds, particularly tris(hydroxyphenyl)alkanes, and to processes for the preparation of such compounds.

This application is a division of copending application, Serial No. 44,547, filed July 22, 1960.

A saturated aldehyde will condense with a hydroxyaryl compound which has a free ortho or para position to give a gem-hydroxyaryl derivative. I have found, however, that aldehydes containing an alpha-beta double bond and an unsubstituted alpha carbon atom will condense to give a tris(hydroxyaryl) propane derivative, in which the third hydroxyaryl group condenses to the double bond.

Accordingly, the present invention provides tris(hydroxyaryl) propane compounds in which the hydroxyaryl groups are attached directly by their ortho or para positions to the chain C-CHCl-I, two of the said hydroxyaryl groups being attached to the said chain by the terminal carbon atom which is shown with a hydrogen atom attached thereto.

It will be understood that the ortho and para positions are relative to the hydroxyl radicals of the hydroxyaryl groups.

The chain is preferably part of an alkyl chain which may be branched.

The hydroxyaryl groups are preferably hydroxyphenyl groups, particularly alkyl substituted hydroxy phenyl groups in which at least one ortho position is occupied by an alkyl radical. Particularly preferred compounds according to the present invention comprise those in which the propane chain forms part of a hydrocarbon chain and is attached to the para positions of three identical hydroxyphenyl radicals to each of which in addition there is a methyl radical at the 3 position and a tertiary butyl radical at the 6 position; the hydroxyl group being regarded as occupying the 1 position.

The compounds of the present invention may be regarded as the non-resinous condensation products of an aldehyde having an alpha-beta double bond and an unsubstituted alpha carbon atom, with one or more hydroxyaryl compounds each having a free ortho or para position, the molar ratio of the hydroxyaryl compound or compounds to the aldehyde being 3:]. I have found that this condensation may be effected in one step in the presence of a condensing agent and a solvent, preferably using at least three moles of the hydroxyaryl compound to The presence of the solvent is essential, and although I do not wish to be bound by any express theory, the solvent is believed to inhibit the formation of resinous products which would otherwise be produced. The solvent must be inert to the reaction material and may for example be methanol or glacial acetic acid.

An condensing agent which is suitable for condensing aldehydes and hydroxyaryl compounds may be used such as Zinc chloride, strong sulphuric acid, or fluorsulphonic acid, but I prefer to use strong hydrochloric acid.

The reaction is preferably carried out at moderately elevated temperatures, for example sufficient to boil the solvent under reflux.

The product may be recovered in any convenient fashion, but if the product is solid. I prefer to add an entraining agent, preferably toluene, when the reaction is substantially complete, and thereafter to distil the mixture until substantially pure toluene distils olf, finally cooling the residue and recovering the solid product which is deposited.

The aldehyde used is preferably aliphatic, and may for example be crotonaldehyde, acrolein, or cinnamaldehyde.

The hydroxyaryl compound used in the reaction is preferably an alkyl phenol such as 3-methyl-6-tert.butylphenol, which has two free reactive positions on the nucleus.

The compounds provided by the present invention are valuable antioxidant-s, particularly in high molecular Weight hydrocarbons such as natural and synthetic rubber and in polyolefines, particularly polyethylene and polypropylene and polyethylene terephthalate. They are particularly useful antioxidants in media in which staining is undesirable, and are effective in such media in minor amounts preferably not exceeding 1% by weight."

EXAMPLE 1 weighed 446 grams corresponding to 82% theoretical yield based on the assumed formula 4 7[ s 2( 3) s s) 13 and had a melting point of 180482" C. The material was recrystallised from petroleum ether (B. Pt. -100 C.) and dried at C. for several hours under high vacuum. The product melted at 188 C. with decomposition.

An acetyl derivative was prepared by treating the product with acetic anhydride and sodium acetate, and recrystallised from ethyl alcohol. The recrystallised derivative showed acetyl groups but no hydroxyl radicals on infrared analysis, and had a melting point of 164 C.

A benzoate derivative was also prepared by treating the product with benzoyl chloride in pyridine.

In Table 1 there are given found and theoretical carbon and hydrogen values and molecular and equivalent weights which show that the formula of the product is C H O in which the oxygen atoms are contained in three hydroxyl groups.

Table 1 Weight percent Material Moi. weight Equivalent weight Product a1 49( )s Acetyl derivative- C21H4s C O 92- Benzoate EXAMPLE 2 I t 3 crystallised product weighed 150 grams and had a melting point of ISO-182 C. V

The following Examples 3 to 7 illustrate the use of different condensation agents which in each case was slowly added to a mixture comprising /3 gram mole of crotonaldehyde, 1 gram mole of 3 methyl 6 tert.butylphenol and 95 grams of methanol stirred under reflux for approximately 30 minutes. The solid which was deposited was filtered 01f; washed withwater and recrystallised as a white solid from toluene. The details of these examples are given in Table 2, in which the product yield percent is based on C H O ,the theoretical formula forthe expected tris product.

I In Example 6 the reaction mixture was saturated with hydrogen chloride gas.

Q i EXAMPLE '12 A mixture of 82 grams of 3 methyl-6-tert.butyl phenol, 50 grams of methanol, and 21 grams of concentrated hydrochloric acid were stirred under reflux, during the slow addition of 3.1,grams of acrolein andfor an hour afterwards. which was washed with further quantities of water and finally dried under vacuum.

A sample of the product from Example '1 was tested as an antioxidant in polythene, polypropylene, polyethylene terephthalate film, and a medium nitrile rubber. The last had a Mooney viscosity index of 89, was of nominal 32% by weight acrylonitrile content, and was prepared by Table 2 Condensing agent Product Example Yield 7 Comments Type Quantity M. Pt., C.

Gms. Percent 8 Cone. hydrochloric acid 35 rule..." 149 82 180-182 Mol. :vt. 02=I=50 (in ace one 4 Cone. sulphuric acid. '7 this 130 72 180-182 Crude product tinged blue-green. V

5 .Fluorsulphonic acid '10 gms 125 69 180-182 Crude product blue. V 6 Hydrogen chloride gas 128 71 180-182 Do. 7 Zinc chloride. '14 gms 116 64 180-182 The following Examples 8 to 10 illustraterthe preparation of crotonaldehyde condensates with difierent phenols, and also a preferred method of product recovery. In each example /3 gram mole of crotonaldehyde was added over 1 hour to a mixture of 1 gram mole of the phenol, tub. of cone. hydrochloric acid, and 95 grams of methanol which was stirred under reflux during the addition. 400 mls. of toluene were then added and the mixture distilled until substantially pure toluene ran as distillate, indicated by an overhead temperature of 110 C. The residue was then cooled, and the resulting White, crystalline solid filtered. Details of Examples 8 to 10 are; given in Table 3, in which product yield percent is v based on the formula for the expected tris compound.

low temperature polymerisation, i.e. at C. The tests V oxidant product and pressing at 150 C. intorsheets and ,4 of an inch thick respectively. Comparative control samples in which, however, the antioxidant was absent were also prepared.

Oven ageing tests were carriedout at 140 C. and 160 C. In the latter case test and control samples of the i of an inch pressings described and measuring 2% Table 3 Product Exam Phenol Yield Found Theory ple M Ch, V

I Grams Percent Mol. wt. 0, wt. H, wt. M01. 0, wt. H, wt. percent percent percent percent 8. 3M6M--. 210-212 47 402;;20 80.3 7.9 418 80.4 8.1- 9 3M6E... 170 '72 47 42l=l=20 31.0 8.7 460 80.9 8.7 i 10 3M60 165 200 84 602=k60 82.5 10.7 712 82.6 10.7

3M6M=3,6-dimethylphenol. 3M6E =3-methyl-6-ethylphenol.

8M60=3-methyl-6-(alpha,alpha,gamma,gamma tetramethyl butyl phenol.

The following examples illustrate the condensation of ditferent aldehydes with 3 methyl-6-tert.butyl phenol.

EXAMPLE 11 30 grams of cinnamaldehyde were added for 30 minutes to a mixture of 82 grams of 3-methyl-6-tert.butyl phenol,

50 grams of methanoland 21 grams of concentrated hydrochloric acid stirred under reflux. By the time the addition was complete the entire reaction mass was solid,

- and was washed with water, dried and recrystallised from xylene The product had a melting point of 260 C.

.and an analysis of C=83.5% and H=8.9%. Theoreti-' cal values for the expected 0 1-1 0 are C=83.2%,

inches long by /s of an inch wide were placed on microscope slides in an air oven. Samples were removed at intervals and the extent of oxidation was estimated by measuring carbonyl group, concentration by infra-redspec- V troscopy using the absorption band at 5.85 microns wavesimilar fashion, except that the antioxidant was incorporated by milling at C. and the samples measuring '1 inch by inch were obtained from'pressings made at C. and of an inch-thick. Theextent of oxidation was measured in the same way, except that the Upon the addition of water a syrup formed time measured was that before the oxygen present as carbonyl was greater than 0.1%

For the oxygen uptake test small samples of the inch test and control pressings were placed in a glass bulb which contained some 5A Linde (registered trademark) molecular sieves and which was connected by a U-tube containing mercury to another glass bulb. (Linde molecular sieves are synthetic zeolites produced and sold by Union Carbide and Carbon Corporation.) Both bulbs, filled with air, were then sealed and the apparatus placed in a vapour thermostat at 140 C. Movement of the mercury indicated oxidation of the polythene and the time in the vapour thermostat at 140 C. until a notable rate of movement of the mercury was apparent, was measured. This time was the induction period for the oxygen uptake test.

(b) Nizrile rubber.--Similar oxygen uptake tests to those described but at 78 C. were applied to thin, raw crepe samples of this material.

(c) Polyethylene ierephthalate.4imilar oxygen uptake tests were applied at 200 C. to a film of this material inch thick, the test sample of which was coated with a 5% solution of the antioxidant in a 50:50 mixture of toluene and acetone. The time recorded was the number of hours required to absorb in each case 20 and 40 cc. of oxygen per gram of sample.

((1) Polypropylene.'lest and control samples of polypropylene were subjected to embrittlement tests as follows.

Polypropylene of melt flow index 5 (as measured by the A.S.T.M. method modified by using a kg. weight instead of that specified for causing extrusion) was mixed on open rolls at 175 C. with twelve ditferent batches of the 3-methyl-6-tertiary butyl phenol/crotonaldehyde condensate, the results quoted in the table representing in each case the averaged results for four different batches.

Thin sheets about 4 of an inch thick were prepared by moulding at 190-195 C. from each of the compositions obtained.

These sheets were held suspended from metal clips in an air oven at 140 C. until they were found to be brittle when handled.

The results of these tests are given in Table 4.

Polyethene and polypropylene samples were also submitted to staining tests. A. sample of the former material in which 1% of the 3-methyl-6-tert.butylphenol-ctotonaldehyde condensate was incorporated showed no colour formation after milling for 3 hours at 160 C.

Samples of polypropylene measuring 1% by /2 by 1& inch and incorporating respectively 0.5 and 0.25% by weight of a condensate, according to the present invention, of 3-methyl-6-tert.butylphenol and crotonaldehyde, were held for 24 hours at a distance of 10 cms. from a 500 watt high pressure mercury arc Hanovia 8-500 source of ultra-violet light, screened by /2 mm. Pyrex glass cutting out light of less than 2850 A. The samples were then compared visually with a scale showing a range from 0=no colour to 6=black. Both were equivalent to 0 on the scale, showing that substantially no staining took place.

I claim:

1. A stabilized composition of matter consisting essentially of polyethylene terephthalate and a stabilizing amount of the condensation product or" a phenol having at least one free reactive nuclear position with an alpha beta unsaturated aldehyde having an unsubstituted alpha carbon atom, the molar ratio of phenol to aldehyde being 3:1.

2. A composition according to claim 1 in which the said phenol is a 3,6-dialkylphenol and the said aldehyde is selected from the group consisting of acrolein, crotonaldehyde and cinnamaldehyde.

said phenol is a 3,6-dialkylphenol attached to said aldehyde at its para position.

Table 4 Induction period, hours Oxygen uptake Oven ageing Embrit- Antioxidant tlement Medium content, wt.

percent 200 C. 78 0 140 C. 140 C. 160 C. 140 C.

20 cc. 40 cc.

Nl 2 2 2 Polythene i 0 3n Name tilt;- d 31:13:23: 1:313:33: 3:31:11:

1 Polyethylene ter- N11 3 ephthalate.

Polypropylenm References Cited by the Examiner UNITED STATES PATENTS 2,801,989 8/57 Franham 260619 2,885 ,3 5/59 Franham 260-619 2,931,697 4/60 Wirth et a1. 260-4535 LEON I. BERCOVITZ, Primary Examiner.

MILTON STERMAN, Examiner. 

1. A STABILIZED COMPOSITION OF MATTER CONSISTING ESSENTIALLY OF POLYETHLENE TEREPHTHALATE AND A STABILIZING AMOUNT OF THE CONDENSATION PRODUCT OF A PHENOL HAVING AT LEAST ONE FREE REACTIVE NUCLEAR POSITION WITH AN ALPHA BETA UNSATRUATED ALDEHYDE HAVING AN UNSUBSTITUTED ALPHA CARBON ATOM, THE MOLAR RATIO OF PHENOL TO ALDEHYDE BEING 3:1. 